To address widespread concerns about cancer risks from residential magnetic field exposures, investigators from NCI and from the Children's Cancer Group are conducting a case-control study of childhood acute lymphoblastic leukemia. Measurement data were collected in current and former residences for 638 cases and 620 controls under age 15, and interview data on prenatal and postnatal exposures to electrical appliances for 640 cases and 640 matched control children. Measurements of magnetic fields in the child's bedroom, the family room, the kitchen and the area immediately outside the front door were used to assess exposure, as were. exposures based on the distance and configuration of power lines (e.g., wire codes) near the subject's home. The exposure of the mother during pregnancy was similarly evaluated. Papers were published in 1997 on the methodology for exposure assessment and childhood leukemia risk in relation to residential measurements. A paper on childhood acute lymphoblastic leukemia risk associated with prenatal and postnatal exposures is currently in revision. Analyses are ongoing on the relationship of residential measurements to wire codes, associations of sociodemographic factors measurements and wire codes, childhood leukemia risk in relation to peak exposures, and more detailed assessment of the variability in residential magnetic field levels between earlier and later residences as well as the effects of estimating residential exposures using measurements from one residence and imputing exposure levels for a second residence among subjects residing in two homes only. We are in the final year of data collection for a case-control study of adult brain cancer (glioma, meningioma and acoustic neuroma) to investigate cellular telephone use and other possible risk factors. In collaboration with investigators in Boston, Phoenix and Pittsburgh, we are enrolling approximately 700 cases and 700 controls who are hospitalized with a variety of nonmalignant conditions. Approximately 75 percent of the targeted numbers of subjects have been enrolled and interviewed. Data collection is expected to be complete in 1998. In response to concerns about cancer risk from non-ionizing radiation of microwave and radio frequencies, an earlier study of cancer mortality among Korean War Naval Service veterans exposed to microwave radiation has been reactivated. Two cohorts of 20,000 men each, who served as shipboard radar operators and maintenance workers, respectively, during their Navy service are being followed for cancer mortality through 1993. Results on the relationship between cancer risk and non-ionizing radiation dose are expected to be available in 1998.